[luv-talk] Demuxing an MPEG TS from a USB PVR where the TS is prefixed with invalid data

Hi all, I have a TV which has a built in USB record feature (which basically dumps DVB-T MPEG TS in 2GB chunks). I'd like to pull the audio track out of something I recorded. VLC happily plays the file and identifies the video, audio and EPG info in the transport stream, but if, for example, I run: avconv -i ... -acodec copy audio.mp3 ... I end up with about 2 seconds of silence. It seems there's a couple of dummy streams and also that the overall file is prefixed with what looks like null garbage. I know that if vlc can play it, there's gotta be a way of extracting it, but must admit that I haven't had any luck thus far. Any ideas on recommended tools for stubborn MPEG TS demuxing? Anthony